6.4 Gen III Hemi on a factory 8.75 rear end

[69ChargerVert]

Curious to hear from folks who have done a hemi upgrade and used the factory 8.75 rear end. I've been told the 8.75 rear end axle tubes won't hold up to the torque of a new hemi and tremec 6 speed. Thoughts?

Thanks,
Tim

 

[5.7 hemi]

HAHAHAHAHHAAAAAAA! Not sure who would say such ****, but they are wrong! Remember the Max Wedge engines had the 8 3/4 behind them and they put out a lot more torque than the modern hemi does.

 

[69ChargerVert]

Cool... do you know what kind of torque ft/lbs the Max Wedge engine put out? I'm to understand with the 6.4 hemi and 6 speed you'll be hitting the 8.75 with aroud 500 lbs of torque.
Thanks 5.7 hemi!

 

[5.7 hemi]

Depends if we are talking factory or race? Factory was somewhere around 470-490 and race was well over that. You'll be fine with the 8 3/4 and street tires.

 

[lxmodguy]

I told him that an 8.75 needed to be reinfiorced and he needs a good aftermarket carrier for it. The car should easily make 500 ftlbs and a 6 speed is going to be hard on it. He wants to build it once and build it right. Thats why my advice was the reinforce the 8.75 and run an aftermarket posi. Being that it is a pro touring car I suggested a wavetrac for it

 

[5.7 hemi]

I agree. Buy once, cry once!

 

[snakeoil24]

it will hold up it's not like it's a real Hemi. Only a small block. You should be fine.

 

[mmissile]

I'm gonna find out............

 

[lxmodguy]

I would rather know it isn't going to break than "find out" when it does. I am an expert at spending money twice, trust me when I say over-engineer your drivetrain so you never have to deal with buying the stuff twice.

 

[snakeoil24]

You guys are nubies, small block motor with 8 3/4 will be fine. Your not putting these little engines behiond a big block or real hemi. We ran 8 3/4 rears for years behind big wedge motors with 4 speed's. So don't worry abou these late model wanna be hemi's they will handle the power. If you where to run a Hemi or big block with sticky tires then a dana 60 would be in order. Your fine with the 8 3/4.

 

[MidWestMopar]

I'm pushing 500+ WHP, 575+ Wheel Torque in my Dart with stock 4 Speed, 8 3/4, and axles....never had an issue. That's not to say I'm not pushing things a bit too far. The 8 3/4 3rd member cases are a little different, the 741 is a little weaker(smaller pinion stem) than the 742 or 489.

 

[69ChargerVert]

Thanks Midwest... after getting perspective from a variety of builders I decided to go the safe route and buy a new Dana 60 from Dr. Diff. That way I know I'm covered. BTW - what motor you running in your Dart?

 

[MidWestMopar]

Thanks Midwest... after getting perspective from a variety of builders I decided to go the safe route and buy a new Dana 60 from Dr. Diff. That way I know I'm covered. BTW - what motor you running in your Dart?

A Procharged Stroker Small block. Very mild, 10psi boost.

 

[69ChargerVert]

Nice! She's a beauty!